1. Clown-esque or un-ordinary.
2. Standing out in a way that is non-conformist, especially to express mockery towards an audience perceived by the non-conformist to be conformist, disingenuous, or otherwise exceptionally robotic in thought, attitude or display.
3. Of or having qualities of the category of harlequins.

"You people are LIFELESS!" the harlequinic man declared, and began juggling ice cream cones and offering licks to all around in between tosses - while humming something from Metallica in a very harlequinic fashion.